1 Answer from the Community

Mini-DVI is single-link and does not support dual-link connections and hence cannot support resolutions higher than 1920×1200 60 Hz (165 MHz pixel clock).

There are some PC's with single-link DVI connectors which actually support higher than 165 MHz clocks (up to 340 MHz) because they are actually HDMI 1.4. In that case, it's possible to use adapters to convert to Dual Link:
1) Single Link DVI to HDMI 1.4
2) HDMI 1.4 to DisplayPort
3) DisplayPort to Dual Link DVI

I don't know if you can overclock the iMac mini DVI port beyond the standard Single Link speed (165 MHz) (it might require a modification to the graphics drivers). Even if you could, all those adapters may cause issues with the signal. I have found that Linux (Ubuntu) supports that chain of adapters better than macOS.